The 8KB pages could also be broken down into 128 byte blocks, so that you could map a (contiguous) portion of a page, and not have to use the whole 8KB. You co

The 8KB pages could also be broken down into 128 byte blocks, so that you could map a (contiguous) portion of a page, and not have to use the whole 8KB. You could also use the same feature to give yourself guard 'pages' (but really guard blocks). It specifically supported the ability to grow down for stacks and guards. And the abort issue is around restarting indirect addressing modes, which will result in repeats of accesses. Technically this is an issue if you were pulling pointers directly out of MMIO regions, but it's one of those "doctor it hurts when I do this." "Then don't do that" kind of situation. If you're getting real cute with advanced addressing using MMIO regions to bounce out to other regions, do that in the kernel (as you probably would be anyway). Then you can do all the fun virtual memory tricks.